A single hot wire switch can be a wireless switch, but the wireless functions need electrical power to work normally. In the past, when the wireless switch is turned off, a wireless control module in the wireless switch gets electrical power supply from an electrical current flowing through a load, such as a light. If the electrical current is too small, the wireless control module cannot work. If the electrical current is too large, the light may have blinking or flickering effects, or dull glow when the light is an incandescent lamp. High resistance power saving lights and LED lights are even more sensitive to the electrical current. Therefore, there is a strong need for a new design of a wireless single hot wire smart switch to overcome the above problems.